1. Field of the Invention
The invention relates to an image processing apparatus for performing a position correcting operation and a correcting operation of spatial frequency characteristics for a plurality of input color component signals.
2. Related Background Art
Hitherto, there has been provided an image reading apparatus having a color separating function by arranging optical filters of different spectral characteristics in front of line sensors to read an image.
In such an image reading apparatus, a method of correcting a positional deviation due to an interpolating operation in order to correct a color deviation which occurs due to differences of the original reading positions of respective colors is known.
FIG. 13 is a diagram for explaining the principle of the correction of such a positional deviation.
In the line sensor coated with filters of red (R), green (G), and blue (B) as shown in the diagram, R, G, and B are regarded as one pixel. Therefore, in order to make the positions of R and B coincide with the position of G, by weighting 1/3 and 2/3 to the adjacent two pixels, the pixels of the respective colors can be falsely set to the same position.
In the case of matching the positions of the pixels by the above conventional method, however, when the color is discriminated every pixel from the ratios of the respective color components, a difference of MTF (spatial frequency transmitting characteristics) occurs, so that there frequently occurs a case where the color cannot be accurately discriminated. Such a problem occurs because since the interpolating operation is not performed to the pixel of G, the MTF of the color of the G pixel is remained to be higher than the MTFs of the other colors.
That is, when the positional deviation is merely corrected, the MTF of the respective color component signals are not matched, so that there occurs a problem such that the signals are not suitable for the color discrimination in such a state.